transponder

noun

tran·​spon·​der tran(t)-ˈspän-dər 

: a radio or radar set that upon receiving a designated signal emits a radio signal of its own and that is used especially for the detection, identification, and location of objects and in satellites for relaying communications signals

Did you know?

This word was coined during World War II by simply joining pieces of the words transmitter and responder. Transponders are basic to modern aviation and communications satellites, and they're finding new uses in fields such as medicine as well. But they're now also part of everyday life. The "E-ZPass" that lets you drive right through turnpike tollbooths is a transponder, and the car you're driving may not even start unless it recognizes the signal from your personal key's transponder. In a big crowded foot race, you may carry a tiny transponder on your shoe that records when you cross both the starting line and the finish line.

Examples of transponder in a Sentence

Recent Examples on the Web

These transponders help maintain a proper balance of creatine and prevent oversaturation within your muscle cells. —Anna Giorgi, Verywell Health, 6 Dec. 2024

But by 40 minutes from takeoff, the plane's transponder, which transmitted its location and altitude, shut down. —Greta Cross, USA TODAY, 20 Dec. 2024

All flying objects, either drones or aircraft, are required to transmit a broadcast signal using a transponder, which lets the FAA know what’s in the airspace. —Brad Dress, The Hill, 17 Dec. 2024

Companies needn’t add transponders, beacons or other extra systems to their satellites. —IEEE Spectrum, 8 Aug. 2024

Word History

Etymology

transmitter + responder

First Known Use

circa 1944, in the meaning defined above